I have AT&T and they have a 1TB data limit. Until recently that has been completely fine, my household usually comes in between 500 and 700 GB a month. However, the past 2 or 3 months, we've been going over the 1 TB limit. I need a way to determine who's hogging the data. Unfortunately my router can't determine this and there's no dd-wrt replacement for it. I'd rather not buy something, since I don't want to use it forever, I just need to figure out what device is using so much so I can fix it. Does anyone know what I can do to find out what device on my home network is eating all my data?

Not really enough info here to suggest much past very general things. You don't say how many people/devices are using your home network, tell us version/distro of Linux involved, or what your network environment is like. Too many variables to guess at. Some routers can cap usage/bandwidth on a per-ip address basis, so you can give different things a static address based on their MAC address via DHCP, then throttle from there.

Things like darkstat can be useful, but you'd have to set up a system that ALL your network traffic runs through. And if you use something like squid to do this, it'll only really work for things like http...so https/scp/torrents/etc., won't necessarily show up, but they still count as bandwidth. Not to mention if someone is using TOR, which can also sometimes be hard to spot.

The first thing I'd do is change my wifi password, just in case someone is piggybacking on my signal.

There are a number of Linux tools for monitoring network usage. This article is a good introduction to them.

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Ok, more info. There's 4 people in my household, I have a Linux server (file, print, NFS), 3 Linux desktops (Kubuntu 20.04 and 22.04), multiple Apple products (iPhones, iPads, laptop).
I have a Linksys Velop mesh router. It shows me all the devices connected and none are unrecognized. It doesn't provide any usage details though.

Ok, but you'll still have to put one Linux system in between your home network and the router to monitor things..otherwise, you're not going to see what's using bandwidth. You could put one of the monitoring tools on each Linux system and check them periodically, and see if one of them is it, but otherwise there aren't many options.

But according to Linksys, you can already do what you want; did you look at their knowledgebase??
https://www.linksys.com/support-arti...icleNum=136118

I checked out your link but that doesn't seem to apply to my router. I've poked around the admin tool many times and don't see anything that contains anything "usage" related. Prior to posting this thread I contacted Linksys support and they said there was nothing in the router admin tool to do this. I had figured I might need to setup my server as a "Proxy Server" but don't know much about it. I guess that's the next step.

Yes, that's what was said previously, that you would have to set up a system (like squid), to sit between your ENTIRE HOME NETWORK and the router. That means, you'll either have to set up that Linux box as your wifi access point and use it, or have everything wired to a hub plugged into that box. And see previous replies about the caveats regarding TOR/bittorrent/https/etc., work with squid and what squid actually is.

I haven't done too much research on Velop devices, but according to what I found, the web interface (not the app) may have functionality that does what you're after. Also, again, you can put monitors on the Linux systems themselves and check them to see what's being used there. If you rule them out, you know it's the other devices. And you need to consider too, that automatic updates on things take a toll. If IOS updates are 500MB (just a random number), and you have multiple, do the math. And that's not taking into account any updates on your computers themselves.

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